A Munster man accused of sending a pipe bomb and threatening note with a bullet to victims is facing additional charges after a grand jury returned an indictment, the U.S. Attorney's office for the Northern District of Indiana announced Thursday.

Eric Krieg, 45, was arrested last month after an FBI investigation following a pipe bomb explosion Sept. 6 at the East Chicago post office on Chicago Avenue.

"When individuals use dangerous, explosive devices as the means to commit or attempt to commit violent acts, those individuals will be held accountable for their actions," said U.S. Attorney Thomas Kirsch in a statement Thursday.

Krieg faces five charges, according to the indictment, including making an unregistered destructive device; mailing a destructive device; malicious use of explosive materials; possessing a destructive device in furtherance of a crime of violence; and mailing a threatening communication.

The indictment lists three victims in Krieg's federal case — an attorney who represented a client in a 2013 lawsuit against Krieg, a postal worker injured in the September explosion, and a person who received a threatening note from Krieg, also in September.

From at least 2012 to August 2017, Krieg "engaged in a series of online postings and communications concerning other residents of Northwest Indiana," including on a blog he controlled, according to the U.S. Attorney's office.

A lawsuit was filed in 2013 in Lake Superior Court "based upon statements Krieg made on his blog," prosecutors said. Krieg filed for bankruptcy, but the lawsuit was ultimately settled and required Krieg pay the individual $45,000 and post an apology on Krieg's blog, according to prosecutors.

On Sept. 6, a pipe bomb went off at a post office at 901 E. Chicago Ave., injuring a pregnant postal worker. She had had cuts, abrasions and bruises to her head, legs and feet, officials said. The woman, who was seven months pregnant, and the baby were doing "fine," a U.S. Postal Inspection Service said last month.

Prosecutors also claim that Krieg sent a second piece of mail to another person at their Hammond residence Sept. 29 that contained a bullet and a message that read, "The next one will be in the back of your head."

A federal judge denied Krieg bond last month, saying "I am convinced he is a danger to others."

Krieg had requested to be released on electronic home monitoring. He previously worked as an engineer at BP and "has very strong ties to the community," said Kevin Milner, Krieg's attorney.

Krieg has no criminal history, attorneys said. He previously ran against Lake County Council member Dan Dernulc in 2011 Republican primary, and then ran against Democrat George Van Til in a Lake County surveyor's race in 2012. He lost both races.

Prosecutors rejected the request, claiming Krieg built the pipe bomb in his Munster home garage, where he lived with his wife and four children.

When Krieg was arrested, he was initially charged through a complaint with the knowing possession of a destructive device and with transporting explosive materials.

Prosecutors have not commented on a motive, but Kirsch said "we believe he specifically targeted the victims."

Krieg is scheduled to appear in federal court again Nov. 20, records show.